The name of a stage appears above the stage in black text. For example, the first Oracle CQL processor is named FindCrossRates and the name of its inbound channel is FxQuoteStream.

The name of the event type transmitted on a given channel is shown above the connecting line in blue text. For example, the event type transmitted on the FxQuoteStream is StockTick.

To navigate to areas of the EPN that are off the screen, click in the miniature EPN view, and drag.

To change the layout of the EPN, select a layout option from the Layout menu:

organic

tree

hierarchic (default)

balloon

orthogonal

To change the way the EPN fits in the browser window:

Click on the Zoom slider and drag to the right to increase the zoom level; drag left to decrease the zoom level.

Click the Fit Content button to automatically adjust the zoom level to make all of the EPN visible in the browser window; click the Actual Size button to reset the zoom level to zero.

Click the Zoom Out (+) button or Zoom In (-) button.

4.2 Viewing and Editing the Configuration of a Stage

Using Oracle CEP Visualizer, you can view the configuration of any stage and change the configuration for some stages.

Note:

Any changes to rules and Oracle high availability adapters are propagated to the other servers in the same group. That is, all rule and and Oracle high availability adapter configurations is automatically synchronized. Other configuration changes are not synchronized. For example, if you change record/playback or JMS adapter configuration on one server in a multi-server domain, then these changes are not synchronized with the other servers in the same group. For more information, see Chapter 18, "Managing Multi-Server Domains"

4.2.1 How to View and Edit the Configuration of a Stage

You can view and change the configuration of a stage using the Oracle CEP Visualizer.

To view and edit the configuration of a stage:

In the left pane, navigate to and expand the Applications node of the Oracle CEP instance to which the application is deployed.

Select appname, where appname is the name of the application you want.

Select the stage you wish to view and configure:

To use the EPN diagram:

Click the Event Processing Network tab.

Double-click the stage you wish to view or Right-click the stage and select Open Panel.

To use the domain tree:

Expand the appname > Stages node, where appname is the name of the application you want to view.

Specifies the maximum number of threads that will be used to process events for this channel.

You can change Max Threads from 0 to a positive integer (that is, from a pass-through to multiple threads) without redeploying. However, if you change Max Threads from a positive integer to 0 (that is, from multiple threads to a pass-through), then you must redeploy your application.

If the Max Size attribute is 0, then setting a value for Max Threads has no effect.

The default value for this attribute is 1.

Event Type Name

The name of the event type that this channel carries.

Timestamp Type

Use this element to specify whether or not the channel is application timestamped, that is, if the application is responsible for assigning a timestamp to each event, using any time domain. Valid values are:

For system timestamped relations or streams, time is dependent upon the arrival of data on the relation or stream data source. Oracle CEP generates a heartbeat on a system timestamped relation or stream if there is no activity (no data arriving on the stream or relation's source) for more than this number of nanoseconds. Either the relation or stream is populated by its specified source or Oracle CEP generates a heartbeat every Automatic HeartBeat number of nanoseconds.

Note: This attribute is only applicable when a non-streaming source is connected to the channel.

Specifies the maximum number of threads that will be used to process events for this channel.

You can change Max Threads from 0 to a positive integer (that is, from a pass-through to multiple threads) without redeploying. However, if you change Max Threads from a positive integer to 0 (that is, from multiple threads to a pass-through), then you must redeploy your application.

If the Max Size attribute is 0, then setting a value for Max Threads has no effect.

Specifies the maximum number of threads that will be used to process events for this stream.

You can change Max Threads from 0 to a positive integer (that is, from a pass-through to multiple threads) without redeploying. However, if you change Max Threads from a positive integer to 0 (that is, from multiple threads to a pass-through), then you must redeploy your application.

If the Max Size attribute is 0, then setting a value for Max Threads has no effect.

4.2.1.16 Cache Properties: Oracle CEP Local Cache

After you click Edit, you can modify the attributes that are not shaded grey. Table 4-4 describes all the attributes on the General tab for this stage.

Table 4-4 Properties: Oracle CEP Local Cache

Attribute

Description

Max Size

Specifies the max-size element to define the number of cache elements in memory after which eviction or paging occurs. Currently, the maximum cache size is 2^31-1 entries. This element may be changed dynamically.

Idle Time

Specifies the number of milliseconds a cache entry may not be accessed before being actively removed from the cache. By default, there is no idle-time set. This element may be changed dynamically.

WriteBehind: Specifies asynchronous writes to the cache store. The cache store is invoked from a separate thread after a create or update of a cache entry. This element may be changed dynamically. For more information, see "write-behind" in the Oracle Complex Event Processing Developer's Guide for Eclipse.

Eviction Policy

Use this element to define the eviction policy the cache uses when Max Size is reached.

Valid values are:

FIFO: first in, first out.

LRU: least recently used

LFU: least frequently used (default)

NRU: not recently used

Time To Live

Specifies the maximum amount of time, in milliseconds, that an entry is cached. Default value is 0 (which means infinite).

4.3 Recording and Playing Back Events in the EPN

The event repository feature of Oracle CEP allows you to record events flowing through an event processing network (EPN) and store them so you can later play back the events. You configure the recording and playing back of events per stage, such as a processor or stream. Additionally, only events coming out of an event source can be recorded, and playback is possible only on event sinks (events are played back to the inbound side of the event sink stage.)

The only configuration options of record and playback that you can control using Oracle CEP Visualizer are event type, time, and speed.

The Record tab in Oracle CEP Visualizer for a particular stage is divided into the following sections:

Recording Current Status: displays the current status of a recording. When the system has begun a recording session, then this field displays a blinking Recording message and it changes back to blank when the recording sessions ends. This section is read-only.

Recording Parameters: specifies the name of the database schema (Dataset name) and the provider information. You must pre-configure the provider for the event repository.

Event Type List: contains the Event Type List pane that displays the list of event types that are associated with a selected stage of the Oracle CEP application. Choose one or more events to record.

Record Schedule Entry: entries in this table displays the recording start time and end time for an event type. The fields in this table are disabled by default. Click Update Record to enable the fields in this table. The start and end time entries are optional fields, to start recording immediately, click the Start Recording button at the bottom of the panel.

Change Recording Schedule: allows you to change some of the properties of your existing recording entry. Certain properties, such as the event type, cannot be changed using Oracle CEP Visualizer. Use the calendar and clock controls to specify or change an existing start and end time for recording events.

Decide what you want to do:

To add a new record schedule entry, click Add.

To modify an existing record schedule entry, select the entry in the Record Schedule Entry table and click Edit.

To delete an existing record schedule entry, select the entry in the Record Schedule Entry table and click Delete.

Oracle CEP Visualizer keeps track of whether a particular stage is currently recording or playing back events; based on this information, the Start and End buttons may be enabled or disabled as appropriate.

When you start recording using Oracle CEP Visualizer, Oracle CEP uses the event type information from your record entry and begins recording immediately; the pre-scheduled time, if any, remains unchanged. Use the End button to stop recording of your session immediately.

The Playback tab in Oracle CEP Visualizer for a particular stage is divided into the following sections:

Playback Current Status: displays the current status of playback. When the system has begun playing back a session, then this field displays a blinking Playback message and it changes back to blank when the playback session ends. This section is read-only.

Playback Parameters: specifies the name of the database schema (Dataset name) and the provider information. You must pre-configure the provider for the event repository.

Event Type List: contains the Event Type List pane that displays the list of event types that are associated with a selected stage of the Oracle CEP application. Choose one or more events to playback.

Playback Filter Entry: specify a set of filters using the clock and time controls, to run a playback for an event type in event type repository. Only events that were recorded during the start and end times you specify here will be played back.

Playback Schedule Entry: entries in this table displays the playback start time and end time for an event type. The fields in this table are disabled by default. Click Update Playback to enable the fields in this table. The start and end time entries are optional fields, to start recording immediately, click the Start Playback button at the bottom of the panel.

Change Playback Filter Parameters: allows you to change some of the properties of the selected playback filter entry.

Change Playback Schedule Parameters: allows you to change some of the properties of the selected playback schedule entry. Use the calendar and clock controls to specify or change an existing start and end time for playing back events.

Click the calendar and clock controls in the Change Playback Schedule Parameters area to add a start time and end time and to specify a speed and repeat mode.

Speed: the default speed value is 1, which corresponds to normal speed. A value of 2 means that events will be played back 2 times faster than the original record speed. Similarly, a value of 0.5 means that events will be played back at half the speed.

Repeat: set this to true to repeat playback until the scheduled end time or until you stop playback manually; set this to false to playback only once.

Oracle CEP Visualizer keeps track of whether a particular stage is currently recording or playing back events; based on this information, the Start and End buttons may be enabled or disabled as appropriate.

When you start playback using Oracle CEP Visualizer, Oracle CEP uses the event type information from your playback entry and begins playback immediately; the pre-scheduled time, if any, remains unchanged. Use the End button to stop playback session immediately.

Decide when you want to stop playback:

If you scheduled a stop time, event playback will stop at that time.

If you want to stop event playback immediately, click Stop.

4.4 Tracing and Injecting Events in the EPN

Using the Event Inspector service and the stream visualizer, you can:

Trace events on any HTTP pub-sub server channel.

Trace events on any stage in the EPN on the Event Inspector service dynamic HTTP pub-sub server channel.

Inject events to any HTTP pub-sub server channel

Inject events into any stage in the EPN using the Event Inspector service dynamic HTTP pub-sub server channel.

Note:

The Event Inspector service is not for use on a production Oracle CEP server. It is for use only during development.

To monitor a channel, click on a channel in the All Channels list and drag and drop it onto one of the four graphs in the Channel Monitor tab.

The channel name is added to a color-coded legend below the graph. The color corresponds to the channel's line in the graph.

The channel name is also added to the Monitored Channels list.

You can display all channels on one graph or distribute channels amongst the four graphs in any combination.

To change the scale of the graphs, click on the slider to the left of the vertical axis and drag it up or down.

To stop monitoring a channel, click the Remove button associated with it in the Monitored Channels list.

4.6 Monitoring the Throughput and Latency of a Stage or Path in the EPN

You can use Oracle CEP Visualizer to monitor the entry and exit points of a stage, or a specified path, of the event processing network (EPN) of an application. Oracle CEP defines the following metrics that you can monitor for each stage or path:

Throughput: The number of events processed by the stage.

Average Latency: The average amount of time it takes an event to pass through a specified path of the EPN, or latency.

Maximum Latency: The maximum amount of time it takes an event to pass through a specified path of the EPN.

Average Latency Threshold: Calculates the average latency values greater than the specified threshold value for specified start and end points.

The Oracle CEP Visualizer monitoring feature is itself implemented as an Oracle CEP application; this means that the diagnostic information can be viewed as an event, and the application uses EPL rules to process these diagnostic events.

4.6.1 How to Monitor the Throughput and Latency of a Stage or Path in the EPN

You can monitor the throughput and latency of a stage or path in the EPN using the Oracle CEP Visualizer.

To monitor the throughput and latency of a stage or path in the EPN:

In the left pane, navigate to and expand the Applications node of the Oracle CEP instance to which the application is deployed.

Select appname, where appname is the name of the application for which you want to monitor throughput and latency.

Select the stage you wish to view and configure:

To use the EPN diagram:

Click the Event Processing Network tab.

Double-click the stage you wish to monitor or the first stage in the path that you want to monitor.

To use the domain tree:

Expand the appname > Stages node, where appname is the name of the application you want to monitor.

Click the stage you wish to monitor or the first stage in the path that you want to monitor.

In the right pane, click the General tab

The stage's General tab appears. For example, Figure 4-48 shows the General tab for a channel.

Specifies that you want to monitor the maximum amount of time it takes for events to flow through a stage or a subset of the event processing network (path).

Average Latency Metric

Specifies that you want to monitor the average amount of time it takes for events to flow through a stage or a subset of the event processing network (path)

Average Collection Interval

Specifies the time interval for which you want to gather diagnostic data. In other words, the sliding window across which the Average Latency Metric is computed.

This value is enabled only if you specify Max Latency Metric.

Threshold

Specify a value if you are interested in only receiving latency metrics that exceed a certain value. For example, if you would like to know when the latency exceeds 250 ms, specify a Threshold value of 250 ms.

This value is enabled only if you specify Average Latency Metric.

Start Stage Name

Specifies the name that you have provided for the start stage.

If you want to monitor just the current stage, rather than a path in the EPN, then set the Start Stage Name and End Stage Name to the name of the current stage.

Select Entry for the Start Stage Name option and Exit for the End Stage Name.

End Stage Name

Specifies the name that you have provided for the end stage.

If you want to monitor a path in the EPN, Oracle CEP Visualizer assumes that the current stage is the start of the path, and thus automatically selects it for the Start Stage Name field.

Specify whether the start of the path should be the Entry or Exit of the current stage. Then, select the End Stage Name, or the end of the path you want to monitor, and specify whether the end of the path should be the Entry or Exit of the stage

Click the Latency tab in the accordion menu as shown in Figure 4-50 and enter the information that Table 4-6 lists.

Specifies that you want to monitor the average throughput of events flowing through the stage.

Stage Name

Specify whether you want to monitor the throughput at the entry or exit of the stage

Throughput Interval

Specifies the period of time for which the throughput is calculated.

For example, if you specify a Throughput Interval of 1 second, the number of events passing through the stage in 1 second will be calculated. This will be averaged over the Average Interval you specify.

Specify the time unit as Second, Millisecond, or Microsecond.

Average Interval

Specifies the interval for gathering the average throughput.

For example, if you specify a Throughput Interval of 1 second, the number of events passing through the stage in 1 second will be calculated. This will be averaged over the Average Interval you specify.

Specify the time unit as Second, Millisecond, or Microsecond.

Click Save.

A pop-up confirmation dialog appears in the lower-right corner of the panel.

The saved diagnostic profile appears in the left domain tree, under the stage from which you created it, as shown in Figure 4-52.

To expand the performance monitoring graphs to fill the screen, click Expand Chart.

To restore the performance monitoring graphs to their original size, click Restore Chart.

The Management Events section at the top of the Dashboard displays alerts about the incoming monitoring events. The Oracle CEP monitoring feature defines a set of default EPL rules that specify when these alerts show up in the Management Events table. You can change the EPL rules to customize this behavior, as described in Section 7.4, "Changing the dataservices Application Event Filter Rule Using EPL."

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